Creating a popup with rounded corners can give your popup a softer, more modern look. Here's how you can adjust the border radius to make popups rounded in Poper.ai:

- Log in to your Poper.ai account.

- From the dashboard, click on "All Popups" to view a list of your existing popups.

- Find the popup you wish to edit from the list and click on it. This will open the popup editor.

- In the popup editor, locate the "Global Settings" section. This should be on the right side of the screen.

- Scroll down to the "Border Radius" option within the "Global Settings."

- Click on the border radius field, which may show a pixel (px) value.

- You can either type in a new value directly into the border radius field or use the slider provided to increase or decrease the value. As you adjust the slider or change the value, you will notice the corners of your popup round according to the pixel value you set.

- The higher the value, the more rounded the corners will become. A small value will result in slightly rounded corners, while a larger value will create a more pronounced rounded effect.

For more granular control over the corner rounding, click the split button located next to the slider. This will allow you to edit the top-left, top-right, bottom-left, and bottom-right corner radius values individually.

- Look at the popup preview area to see how the rounded corners appear in real-time.

- Once you are satisfied with the appearance of your popup's rounded corners, click the "Update" button to save your changes.

- After saving, it's a good practice to test how the popup looks on your website to ensure that the rounded corners are displayed as expected on different devices and browsers.

By following these steps, you can easily give your popups a modern and stylish look with rounded corners on the Poper.ai platform.